In the supercritical fluid chromatography apparatus, a supercritical fluid is used as a mobile phase. The supercritical fluid has higher diffusibility and lower viscosity than those of an ordinary solvent. Therefore, by using the supercritical fluid chromatography apparatus, for example, it is possible to separate at high speed an optical isomer which is difficult to separate.
In such a supercritical fluid chromatography apparatus, a supercritical fluid formed of carbon dioxide or the like is used as the mobile phase, and, after injecting a sample into the mobile phase and dissolving components of the sample in the mobile phase, the components of the sample in the mobile phase are separated by regulating a pressure, a temperature, and the like of the mobile phase. Alternatively, a mobile phase is formed by mixing the supercritical fluid with a solvent such as ethanol referred to as an entrainer or a modifier, and separation is performed by regulating a pressure, a temperature, and the like of the mobile phase.
In Patent Document 1, there is proposed a technology of detecting and washing off components having a large molecular weight and no ultraviolet absorption from a column by providing a second injector on an upstream side of a sample injector and by coupling an output side of a constant pressure release valve with a light diffusion detector.
Further, in Patent Document 2, there is proposed a technology of fractionating and recovering a sample by performing elution while sequentially replacing solvents each having different solvent strength when the sample is eluted from a column in which the sample is absorbed by using a supercritical fluid into which the solvents are added as modifiers. However, in these technologies, examination has not been made in view of improving efficiency in fractionation, particularly of fractionating large amounts of target substances from the sample by sequentially injecting the samples, and thus these technologies are not suitable for industrial mass production.